La Nina weakens as rainfall season nears end

Sifelani Tsiko

Innovations Editor

As the weak La Niña event that emerged in December 2024 transitions to neutral conditions, above-average rainfall is likely to diminish in Zimbabwe and other countries in the region as the summer cropping season comes to an end, the latest report from the World Meteorological Organisation Global Producing Centres for Seasonal Prediction says.

“Seasonal forecasts for El Niño and La Niña and the associated impacts on weather and climate patterns globally are an important tool to inform early warnings and early action and are one of a wide suite of services offered by the WMO community to support decision-making,” said WMO Secretary-General Celeste Saulo.

“These forecasts translate into millions of dollars in economic savings for key sectors like agriculture, energy and transport and saved thousands of lives over the years by enabling disaster risk preparedness.”

El Niño tends to raise global temperatures while La Niña tends to be slightly cooler, experts say.

The 2024-25 rainfall season in Zimbabwe and other countries in the region coincided with a weak La Niña phase that brought better rainfall.

Prof Desmond Manatsa, a climate scientist and head of the Climate Change Resilience Building Innovations Centre at Bindura University of Science Education said southern Africa’s climate is strongly influenced by large-scale climate patterns like El Niño-Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD).

“During extreme phases of these systems, rainfall patterns shift dramatically. El Niño typically suppresses rainfall, while La Niña enhances it. Similarly, a positive IOD often reduces rainfall, whereas a negative IOD boosts it,” he said.

“The season began under ENSO-neutral conditions, but a shift to La Niña occurred in late November. This change allowed the Intertropical Convergence Zone (ITCZ)—a key rain-bearing system—to shift further south than usual, moving from DR Congo into southern Africa,” said Prof Manatsa.

“The result was not just increased, but widespread, above-average rainfall across much of Zimbabwe, bringing hope for a successful agricultural season.”

“As La Niña is expected to weaken and transition back to a neutral ENSO state by mid-March to early April, the ITCZ is likely to become less active over the region. This timing aligns with the typical end of Zimbabwe’s rainfall season, which usually winds down around mid-March.”

The Meteorological Services Department continues to monitor daily weather patterns and provide rainfall updates to guide farmers and stakeholders through these transitions.